U.S. patent number 6,918,525 [Application Number 10/443,854] was granted by the patent office on 2005-07-19 for spring energized desktop stapler.
This patent grant is currently assigned to WorkTools, Inc.. Invention is credited to Joel Marks.
United States Patent |
6,918,525 |
Marks |
July 19, 2005 |
**Please see images for:
( Certificate of Correction ) ** |
Spring energized desktop stapler
Abstract
A desktop stapler uses a spring to store energy to install
staples by impact blow. The force required to fasten papers
together is reduced. A very compact mechanism is used, including a
dual coil power spring with a nested lever. A multi function base
provides a sloped front all the way to down to a desk top surface
to guide paper sheets atop the base, easy access for lifting the
stapler off a desk, horizontal or vertical resting positions, and
integrated soft grip under-surface. The base surrounds the rear of
the stapler body to provide a smooth exterior so that the device is
natural to use both horizontally and vertically. A simple re-set
spring provides a smooth re-set action as the handle is raised. A
staple track includes enlargement features to fit a larger staple
pusher spring.
Inventors: |
Marks; Joel (Sherman Oaks,
CA) |
Assignee: |
WorkTools, Inc. (Chatsworth,
CA)
|
Family
ID: |
33450514 |
Appl.
No.: |
10/443,854 |
Filed: |
May 23, 2003 |
Current U.S.
Class: |
227/120; 227/119;
227/125; 227/126 |
Current CPC
Class: |
B25C
5/0242 (20130101); B25C 5/0292 (20130101); B25C
5/10 (20130101); B25C 5/1696 (20130101) |
Current International
Class: |
B25C
5/00 (20060101); B25C 5/02 (20060101); B25C
005/00 () |
Field of
Search: |
;227/83,119,120,125,126,132,134 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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DT2856-621 |
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Dec 1978 |
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DE |
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10138447 |
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Jul 2003 |
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DE |
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10225816 |
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Jan 2004 |
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DE |
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2 032 327 |
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Oct 1979 |
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GB |
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2 229 129 |
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Sep 1990 |
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GB |
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Primary Examiner: Huynh; Louis K.
Assistant Examiner: Chukwurah; Nathaniel
Attorney, Agent or Firm: Feng; Paul Y. Fulwider Patton Lee
& Utecht, LLP
Claims
What is claimed is:
1. A stapling device for dispensing staples comprising: a handle
pivotably mounted to a housing body; the body having a front end
and a hinge connection proximate to a rear end; a base pivotably
engaging the body at the hinge connection; a striker slidably
disposed in the body proximate to the front end thereof; a track
disposed beneath the striker for holding the staples, wherein the
striker is biased to move toward the track to impact the staples; a
lever having a front end, a back end, a pivot axis therebetween,
and a tab in between the pivot axis and the back end, wherein the
pivot axis pivots against the body, the handle rotatably engages
the tab, and the lever front end selectively lifts the striker
against the bias, and wherein the lever pivot axis includes an
elongated slot pivotably and slidably mounted to the body so that
the re-set spring further urges the lever to slide linearly toward
the body front end; and a re-set spring disposed rearward of the
lever pivot axis and engaging the lever back end and body, urging
the lever front end toward the track to re-engage the striker.
2. The stapling device of claim 1, wherein the tab includes a
convex surface that slidably engages the handle.
3. The stapling device of claim 1, wherein the lever front end
includes a striker engagement surface, and wherein the striker
engagement surface, a tangent through the elongated slot, and an
engagement surface of the tab are all contained in a common
horizontal plane.
4. The stapling device of claim 1, wherein the re-set spring
includes an angled end that hooks through a hole at the lever back
end pulling the re-set spring toward the lever.
5. The stapling device of claim 1, wherein the stapling device
further comprises a double coil torsion spring straddling the lever
between the coils and having two ends that engage the striker
urging the striker toward the staple track.
6. A stapling device including a body and a handle pivotably
attached to the body at a rear of the stapling device wherein: the
handle has a rest position where the handle is pivoted to an upper
position away from the body, the handle has a pre-release position
where the handle is pivoted down toward the body, and the handle
has a re-set position intermediate between the rest position and
the pre-release positions; a striker is movable within the body and
is linked to the handle through a lever whereby pressing the handle
toward the body causes the striker to rise in the body; the handle
presses a lever tab at a rear of the lever and the lever pivots
about a lever axis within the body; a power spring within the body
is linked to the striker whereby raising the striker causes the
power spring to deflect and store energy; at a predetermined
position of the handle the lever suddenly releases the striker and
the striker ejects a staple out of a staple loading chamber as the
power spring returns to a rest position; a re-set spring pushes
upward upon the lever at a rear portion of the lever behind the
lever axis, the re-set spring causing a downward bias upon a front
portion of the lever; the re-set spring engaging the lever at a
position rearward of both the lever tab and the lever axis; wherein
a re-set stroke of the lever includes a first step where the lever
front distal end moves from above the striker downward to a toy
edge of the striker, a second step where the lever front distal end
moves to behind the striker, and a third step where the lever front
distal end moves forward into a slot in the striker; the re-set
spring comprises a torsion spring, a lower arm of the torsion
spring pivotally attached to the body, an upper arm pivotally
attached to the lever, a coil of the re-set spring positioned
forward from the attachments of the upper and lower arms and
movable with the body; the re-set spring pushes upward upon the
lever during the first step and second steps, and the re-set spring
pushes upward and forward upon the lever during the third step; the
coil of the re-set spring moves rearward as the arms of the reset
spring move apart during the re-set stroke, the coil of the re-set
spring contacts a rib of the body during the third step of the
re-set stroke.
7. The stapling device of claim 6 wherein the lower arm includes a
bent segment that extends into a hole of the body, the hole being
larger in diameter than wire of the re-set spring and defining a
pivot axis for the lower spring arm, the bent segment has at its
distal end a further bent portion, the bent portion pressing into a
wall of the hole.
8. A stapling device including a body and a handle pivotably
attached to the body, a staple loading chamber, a track within the
loading chamber to hold and guide staples in the stapling device, a
staple pusher to urge staples on the track toward a front of the
stapling device, a striker to eject staples at a front of the
loading chamber out of the stapling device wherein: the body
includes two assembled halves defining an interior space of the
body; the handle includes bosses that engage recesses within the
body, the bosses and recesses defining a pivot location of the
handle upon the body, the handle bosses extending outward from the
handle, the recesses extending into sidewalls of the interior space
of the body; the handle able to be installed into an assembled
position in the interior space of the body by forcibly separating
the halves of the body.
9. The stapling device of claim 8 wherein at least one of the body
and the handle bosses include chamfers to assist in separating the
halves of the body as the handle is forced into the assembled
position.
10. A stapling device for dispensing staples comprising: a handle
pivotably mounted to a housing body; the body having a front end
and a hinge connection proximate to a rear end; a base pivotably
engaging the body at the hinge connection; a striker slidably
disposed in the body proximate to the front end thereof; a track
disposed beneath the striker for holding the staples, wherein the
striker is biased to move toward the track to impact the staples; a
lever having a front end, a back end, a pivot axis therebetween,
and a tab in between the pivot axis and the back end, wherein the
pivot axis pivots against the body, the handle rotatably engages
the tab, and the lever front end selectively lifts the striker
against the bias; a re-set spring disposed rearward of the lever
pivot axis and engaging the lever back end and body, urging the
lever front end toward the track to re-engage the striker; and
wherein the lever includes a relatively straight flat plate having
a slight bend in a central portion to accommodate the re-set spring
proximate thereto.
11. A stapling device for dispensing staples comprising: a handle
having a front end and a pivot proximate to a rear end; a housing
body having a front end and hinge connection proximate to a rear
end, wherein the handle pivot engages the body forward of the hinge
connection; a base having a front and a rear wall with opposed
sidewalls, wherein the body hinge connection pivotably engages the
base at the sidewalls; a striker slidably disposed in the body
proximate to the front end thereof; a track disposed beneath the
striker within the body for holding the staples, wherein the
striker is biased to move toward the track to impact the staples; a
lever having a front end, a back end, a pivot axis therebetween,
and a tab in between the pivot axis and the back end, wherein the
pivot axis pivotably engages the body, the handle selectively
engages the tab, and the lever front end selectively lifts the
striker against the bias; a re-set spring disposed rearward of the
lever pivot axis and engaging the lever back end and body, urging
the lever back end away from the track and lowering the lever front
end to re-engage the striker; and wherein the lever pivot axis
includes an elongated slot pivotably and slidably disposed on the
body so that the re-set spring further urges the lever to slide
linearly toward the body front end.
Description
FIELD OF THE INVENTION
The present invention relates to desktop staplers. More precisely
the present invention discloses improvements to a spring-actuated
stapler.
BACKGROUND OF THE INVENTION
In a common desktop stapler a striker is linked directly to a
handle so that pressing the handle ejects a staple out and through
a stack of papers. Three distinct forces must be overcome: breaking
off the staple from the rack of staples, piercing the papers, and
folding the staple legs behind the papers. As the staple moves
through the cycle there are force peaks and force lows. The result
is a jerky experience as the user forces the handle down. The
handle resists, suddenly gives way, and then resists again. Even
though the peak forces are for short durations, they define the
difficulty of using a stapler. Empirical information suggest that a
conventional stapler requires peak forces of 15 to 30 pounds,
depending on the number of paper sheets to be fastened.
It is desirable to limit the peak force required. An effective way
to do this is to accumulate the total energy needed to install the
staple and then release that energy all at once by striking the
staple in an impact blow. This is a type of action commonly used in
staple gun tackers. A handle is pressed through a range of motion
causing a spring to store energy. The stored energy is suddenly
released at a predetermined handle position. A striker linked to
the spring ejects and installs a staple. released at a
predetermined handle position. A striker linked to the spring
ejects and installs a staple.
An important advantage of using stored energy to install a staple
is that the handle end need not be directly linked to the striker.
In a common direct acting desktop stapler the handle front end
moves exactly as the staple moves. This means that, for example, 15
lbs to force a striker, thus a staple, to move 1 mm requires 15 lbs
to move the handle that same 1 mm. If the driving energy is stored,
then the handle can be delinked from the striker. The handle can
move more than the striker moves to provide enhanced leverage. For
example the handle, where it is pressed near its front end, may
move downward one inch as the spring is deflected, while the
striker moves just 1/2 inch when the spring is released. According
to the preceding discussion, the peak force in stapling can be
reduced through two ways. First, using stored energy allows removal
of force peaks by averaging forces over a full handle motion.
Second, the energy can be stored through a leveraged system.
A stapler must have a method for adding staples to a staple track.
In a common direct acting stapler the striker has a rest position
immediately above the staple to be ejected. The track may move
outward from the front of the stapler to expose a staple loading
area since the striker does not obstruct such motion. Or the handle
may be linked to a staple pusher whereby pivoting the handle away
from the track causes the pusher to retract while the track becomes
exposed.
In a practical spring actuated stapler these two common loading
systems are not easily provided. The striker rests in its down
position just in front of the staple rack. It is not possible to
slide the track out past the obstruction created by the striker.
Further, since there is an energy storage mechanism linking the
striker to the handle in the spring-actuated stapler, it would
require a complex design to provide for exposing the staple track
by pulling the handle away from the track. An alternate staple
loading design is needed.
Among the prior art is UK Patent GB2229129. A spring actuated
heavy-duty desktop stapler includes a two piece molded housing with
a double torsion (two coil) power spring. A lever has a "U" channel
section, and engages an extended handle by means of a roller
linkage.
German Patent DT2856-621 shows a staple gun that uses a similar
mechanism to the above '129 reference, but as a staple gun tacker,
without a base or a forward handle linked to the lever.
U.S. Pat. No. 4,463,890 discloses a standard style desktop stapler
with a spring-actuated driver. The striker has a raised rest
position, above the staples as in typical direct action staplers.
Base 10 overhangs rubber footpads under the base at the distal
front and rear ends of base 10.
U.S. Pat. No. 2,271,479 shows a stapler with footpads slightly more
closely integrated with the base. The front footpad angles upward
and forward to meet the lower edge of the base, leaving a notch
under the base.
UK Patent GB2032327 shows re-set spring 12 attached to lever 3
rearward of lever pivot 4.
U.S. Pat. Nos. 5,988,478 and 6,145,728, to the present inventor,
show forward action staple guns. In both references the lever has a
"U" channel section that partially surrounds the power spring from
above. In '728 lever 60 engages striker 80 by two opposed openings
83. Power spring 70 fits into striker opening 87 between the
opposed lever openings. In '478, the handle is pivoted to the body
by arcuate extensions 32 surrounding post 12.
U.S. Design Pat. Nos. 186,342, B396,377, D413,239, D437,754, show
various base designs. A short center portion of the base is
actually or visually raised in these designs.
U.S. Pat. No. 5,699,949 to the present inventor shows a further
forward action staple gun. A staple track is at the bottom of the
device, behind the numeral 50 in FIG. 1, formed as an upright "U"
metal channel. A staple track guiding tab of the track is seen just
to the left and above the numeral 5 in FIG. 1. An opening is seen
in the side of the track from which the tab has been formed. A
pusher spring resembling a cross hatch shows through this opening
in FIG. 1. The tab is made from a cut out portion of the side of
the "U" channel.
U.S. Pat. No. 2,218,794 shows a spacer spring 39 that serves a
function to releasably limit upward motion of the body through a
snap fit. Elongated "ears or bearings 11" position the body
laterally above the base in a conventional way by contact between
the body sides and the elongated bearings 11. Spring 39 includes
various out-of-plane bends to allow it to change length as the body
closes against the base. It is therefore not stiff in the lateral
direction. Further, rivet 38 does not provide substantial lateral
stiffness to spring 39.
U.S. Pat. No. 4,546,909 shows a stapler with a spacer spring a3 or
a4 formed as a "punched out" element.
U.S. Pat. No. 4,795,073 shows a spacer spring 19 that is apparently
molded as part of the base.
U.S. Pat. No. 4,811,884 shows a base with a rearward attachment to
the body. Groove 107 engages tab 108 to hold the base in the fully
open position, col. 9, lines 5-13.
In the present invention a desktop stapler includes improvements to
increase ease of use and modes of use. A spring is linked to a
striker so that when the striker is raised and suddenly released
the stored energy of the spring drives a staple through a stack of
papers to be fastened together. A handle is pressed to raise the
striker and store energy in the spring. Improvements of the
invention include: a very compact mechanism to maintain a
conventional looking size of the stapler, a smooth re-set action as
the handle is raised, a simplified handle pivot connection and
assembly method, a spring to raise the stapler body away from the
base where the spring is integrated into a base cover plate, the
base cover plate further including a staple forming anvil, a press
fitted connection between the body and the base, a novel method to
accurately position the body front end over the anvil, a location
for a staple loading track that is convenient and compatible with a
striker that maintains a lowered rest position, a rear distal end
of the body resiliently engages a rib of the base to create a
releasable detent holding the body in a maximum up position from
the bias of the body raising spring, and a base that is raised
along the majority of its length and is convex in its underside to
facilitate lifting the stapler off a table. A further operational
mode allows that the stapler rests on a desk in a front down
vertical position so that it may be most easily lifted up for
use.
A staple loading system includes a track pull element that is
normally hidden from view. Pivoting the body up from and rearward
of the base exposes the track pull for operation.
An advantage of the present invention is that the low operating
force makes it easy to use with an extended hand on a desk. It is
even practical to press by fingertips.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is an upper left side view of the stapler of the
invention.
FIG. 2 is an upper front right side view of the stapler of FIG.
1.
FIG. 3 is an upper right side view of the stapler in a vertical
orientation.
FIG. 4 is a bottom right side view of the stapler of FIG. 3.
FIG. 5 is a rear-left side view of the stapler with the left
housing half removed, and the handle partly in section.
FIG. 6 is a rear-right side view of the stapler of FIG. 5, with the
right housing half removed, and the handle partly in section.
FIG. 7 is a side view of the stapler of FIG. 5.
FIG. 8 is a side view of the stapler of FIG. 6.
FIG. 9 is the stapler of FIG. 8, with the mechanism in a prerelease
position.
FIG. 10 is the stapler of FIG. 7, with the mechanism in a
prerelease position.
FIG. 11 is the stapler of FIG. 7, with the mechanism in a re-set
stroke.
FIG. 12 is a side-rear exterior view of a left housing half of the
stapler.
FIG. 13 is a front-left side view of the stapler, with the body
partially raised.
FIG. 14 is a top view of the stapler, a lever in hidden view.
FIG. 14a is a partial side sectional view of the stapler of FIG.
14.
FIG. 14b is the view of FIG. 14a, with the body pivoted upward.
FIG. 14c is a partial sectional view of the stapler of FIG. 14.
FIG. 15 is an upper-right side view of the stapler, with the body
pivoted fully to the rear of the base.
FIG. 16 is the stapler of FIG. 15, with the track opened for staple
loading.
FIG. 17 is an upper-right side view of a stapler base.
FIG. 18 is a partial sectional side view of the base of FIG. 17,
with a cover plate assembled to the base.
FIG. 19 is a top view of the base assembly of FIG. 18.
FIG. 20 is a partial sectional lengthwise view of the base of FIG.
19.
FIG. 21 is a bottom view of a stapler handle.
FIG. 22 is a bottom-left view of the handle of FIG. 21.
FIG. 23 is a top-right view of the handle of FIG. 21.
FIG. 24 is a lower-side rear interior view of a right housing
half.
FIG. 25 is a lower-side rear interior view of a left housing
half.
FIG. 26 is an isometric view of a power spring in a rest
position.
FIG. 27 is an isometric view of a lever.
FIG. 28 is an isometric view of a striker.
FIG. 29 is an isometric view of a slip link.
FIG. 30 is an isometric view of a re-set spring in a rest
position.
FIG. 31 is a lower-front right side view of a track assembly.
FIG. 32 is an upper-front right side view of the track
assembly.
FIG. 33 is a front view of the rack assembly within a cut-away
portion of a staple-loading chamber.
DETAILED DESCRIPTION
FIGS. 1 and 2 show a desktop stapler according to the invention in
a substantially horizontal orientation, as it would sit upon a
desktop. Base 20 can be seen with a raised elongated central under
portion or surface 24 and front and rear foot sections 25 and 26.
Base 20 may be made from plastic such as glass filled
polypropylene, polycarbonate etc. Body 10 includes a left half,
FIG. 25, and a right half, FIG. 24. Body 10 may be made from high
strength low friction nylon. However other materials may be used
such as other plastics or die cast metal. Die cast metal may be
desirable if higher weight is needed for design preference. Cover
plate 50 encloses cavity 27 of base 20, FIG. 20 to define a central
top surface of base 20. Anvil 57 is formed into the material of
cover plate 50. Alternately anvil 57 is a separate and possibly
movable steel element from cover plate 50. In this case cover plate
50 may be of a plastic or other non-ferrous material. Pivotable
handle 30 fits to housing 10. Optional inset 37 includes decorative
or instructive graphic information. Handle 30 includes a front face
bounded on two sides by corners 35. Corners 35 gradually become
more rounded toward the top of the handle, remaining sharp at least
to the position of contact with surface 200 in FIGS. 3 and 4.
Sidewalls 23 of base 20 surround housing 10 to an upper rear of
housing 10. The front end of base 20 includes a top face of front
foot section 26. This top face is sloped down to a first edge 21 of
the rigid material of base 20. The front face of footpad 121
continues to slope down and forward to a lowermost level of the
stapler, edge 121a, FIG. 8. Footpad 121 is part of rubber or
elastomer overmold 120, FIG. 4. Footpads 121 and 122 extend across
the width of foot sections 25 and 26, and are connected by an
elongated narrow central section of overmold 120. Overmold 120 thus
forms an hourglass shape with a long neck section, FIG. 4. The
exposed rigid material of underside 24 is relatively slippery so
that fingers may easily slide under base 20. The narrow strip of
overmold 120 along the center of underside 24 helps a user keep a
grip on the stapler after the fingers are in position around the
stapler.
Handle 30 between corners 35 may be straight or concave. It is
slightly concave in at least one portion as seen in FIG. 14. The
front face defined by corners 35 allows the stapler to be stable in
a vertical position on a desk, FIGS. 3 and 4. Surface 200
represents such a desk. The vertical position is most convenient
for users that wish to normally lift the stapler for use by
squeezing. The convex sectional shape of the length of under
portion 24, FIG. 20, makes squeezing especially comfortable. Other
shapes could be used such as segments that approximate a convex
shape. Edge 24a, FIG. 20, defines a highly raised edge of the
central portion of the base, near the level of the top of cover
plate 50, so that fingers can easily grip under the stapler. This
highly raised edge extends along each side of the base effectively
making the bottom of base 20 much higher off a surface than it
would be if the entire underside were at its lowest level, the
position of centrally aligned overmold 120 in FIG. 20. It is
desirable to keep the level of cover plate 50 on base 20 as low as
possible so that papers do not need to be raised too high for
stapling. At the same time a limitation to raising the level of
under portion 24 is that the thickness of base 20 must be
sufficient to maintain adequate stiffness of the base. Therefore
using a low center with higher edges 24a, joined by a convex
sectional shape below with a flat top provides a low but thick base
comprising an approximate "D" shape that is easy to grip under.
Foot sections 25 and 26 comprise a short portion of the length of
base 20, being separated by a long straight portion including
convex underside 24. In fact foot section 25 at rear footpad 122
contacts a horizontal surface at just two points, 122a, FIGS. 7 and
18. Edge 24a extends from near a forward most, lowest point of base
20, near callout 26, FIG. 1, up to a long straight segment near the
level of cover plate 50, and down to a rear most, lowest point of
base 20, near callout 25, FIG. 1.
Three points support the stapler in the vertical position, the two
corners 35, and base front end 28, preferably at the central
forward edge of footpad 121. As a design choice front end 28 may be
flat, with respect to a top view, to provide a longer support
surface. However in the illustrated embodiment most of the weight
in the vertical position is supported at the handle, so corners 35
provide good support. As seen in FIGS. 3 and 4, corners 35 do not
need to contact surface 200 at a lower most edge, but rather the
handle front may be shaped so that contact with surface 200 is at a
handle surface more to the right in FIGS. 3 and 4.
The forward edge of footpad 121 extends to sharp edge 121a, FIGS. 7
and 18. In each of the horizontal position of FIG. 1 and the
vertical position of FIG. 3 this edge of soft material touches a
desk surface. The front face of footpad 121 is aligned with edge
21. Optionally edge 21 could be stepped behind the front face of
footpad 121. Combined with the downward sloped base front including
rigid edge 21, a continuous ramp is provided to lift a paper sheet
off a table and guide the sheet up onto cover plate 50. In the
horizontal position there is no gap or undercut to catch a sheet
under edge 121a of base 20. Edge 21 should not be stepped forward
since the resulting ledge would catch a paper sheet sliding up
footpad 121 of the ramp. Overmold 120 includes front footpad 121
and rear footpad 122.
FIGS. 5 and 6 show internal elements of the stapler of the
invention in a rest position. See also FIGS. 21 to 32. In FIG. 5
the left housing half is removed to expose the interior, while in
opposite view FIG. 6, the right housing half is removed. In each
view the respective side of handle 30 is cut away. Handle 30 pivots
about bosses 32, FIG. 21, within recess 12 of body 10, FIGS. 24 and
25. Lever 40 pivots about pin 49 at slot 46, FIG. 27. Pin 49 fits
within cavity 149 of housing 10.
To best fit the components of the stapler in a compact body shape,
a single relatively thick plate lever 40 is used rather than a
thinner steel inverted U channel lever design. Lever front end 48
thus extends through single central slot 108 under a tall center
portion of striker 100, FIG. 8. Lever 40 includes a centrally
aligned front portion and a rear portion out of plane from the
front portion, defined at bend 43, FIG. 14. The rear portion is to
one side in body 10, into the page in FIGS. 6 and 8, to allow
clearance for the coil of re-set spring 70. Tab 44 extends back
across the centerline of the body, out of the page in FIGS. 6 and
8. Tab 44 provides an engagement surface upon which handle 30 can
press.
Preferably handle 30 presses tab 44 through a low friction linkage.
In FIG. 22 slip link 130 is shown attached to handle 30. Stem 138,
FIG. 8, extends by a friction fit into a cavity of handle 30 to
secure slip link 130 to the handle. In normal use tab 44 presses
upward so that slip link 130 can not-fall out of position. Slip
link 130 is made from a low friction material such as Teflon or
acetal such as Delrin 100ST. Optionally handle 30 could be made
entirely from such a low friction material, but it would be much
more costly to produce than if only slip link 130 is of the low
friction resin while handle 30 is of olefin, ABS or other common
structural plastic. Alternately a roller or a pivotable arm could
be attached to either of handle 30 or lever 40 to provide a low
friction linkage between the elements. Slip link 130 includes guide
wall 134 to help position handle 30 within housing 10. Curved
surface 131 presses tab 44.
Striker 100 is fitted along two edges in guide channels 11 of
housing 10, FIG. 5. The location where slip link 130 presses tab 44
is substantially coplanar with slot 46 and lever front end 48.
Lever 40 is flat in the area of slot 46. In FIG. 14 this is
approximately the plane of section cuts 14a,b. This alignment is
important with the single thickness lever 40 to prevent twisting
forces upon lever 40. Non-aligned linkages could cause the lever to
twist and bind within body 10 since it is not inherently stable
like a less compact U channel.
Power spring 90 stores energy for installing staples. Spring 90 is
linked to handle 30 through lever 40 and striker 100. Lever 40
pivots about pin 49 at slot 46 to raise striker 100 at lever front
distal end 48, FIGS. 9 and 10. Rising striker 100 in turn deflects
the front end of spring 90 up by linkage to the spring at openings
102, FIG. 5. In the illustrated embodiment handle 30 moves downward
at its front end about 0.9 inch. This is approximately double that
possible with a direct action stapler where the handle is directly
linked to the striker. The increased handle travel provides
additional leverage to deflect spring 90, thus allowing reduced
handle force. Spring 90 is preferably a double torsion spring, with
co-axial helical coils to each side of lever 40, with the coils
linked at rear end 94; lever 40 passes between the coils. Lever 40
pivots about an axis defined at pin 49. Spring 90 pivots about an
immediately higher axis defined by sleeve 148, FIGS. 24 and 25.
Preferably sleeve 148 of housing 10 surrounds pin 49 to both
position pin 49 and give low friction support to the interior of
the coil of spring 90, FIGS. 9, 24 and 25. Sleeve 148 is
cylindrical or equivalent in function to define an axis of pivoting
for spring 90. A large low friction support surface increases the
efficiency and cycle life of spring 90 as the spring wire slides
against the sleeve. If the spring rubs on a small steel pin rather
than a larger molded plastic surface, the spring will wear quickly.
As shown, sleeve 148 defines an axis that is slightly off center
from pin cavity 149, FIG. 24, with the lower wall of sleeve 148
being thin to the limit of what can be reliably molded. This allows
spring 90 to pivot about the highest possible position, nearly but
not precisely co-axial with the lever pivot defined by pin cavity
149. A low position of the spring coil would cause the angle
between spring ends 92 and striker 100 to become large at the
striker's upper most position of FIGS. 9 and 10. A large angle
would force the striker forward causing excess friction between the
striker, spring, and channels 11.
FIGS. 9 and 10 show a pre-release position of the stapler
mechanism. Lever front end 48 is just out of the plane defined by
striker 100, no longer engaged with slot 108. Striker 100 is free
to accelerate downward under the stored energy of spring 90, to
install a staple. Note that the handle interior is very near to top
edge 103 of striker 100. Top edge 103 is adjacent to upper end 11b
of striker channel 11. Handle 30, shown in cut away, is therefore
in a lower most possible position. To fit lever 40, spring 90 and
striker 100 in a reasonably sized device resembling a desktop
stapler requires a very compact design. A limitation is that handle
30 should be able to fully lower against body 10 as defined by the
striker top most position. The upper surface of handle 30 is
strongly rounded to make the handle comfortable to grip and not
appear large. The top of body 10 is similarly rounded, being
tallest at the center of its thickness. Striker 100 is then also
peaked at top edge 103 to provide the maximum possible striker
material within body 10 that is compatible with the striker
uppermost position. Lever end 48 can therefore nearly approach the
very top of the interior of rounded body 10 in an uppermost
position. Two ends 92 of the double torsion spring fit into
openings 102 below and to each side of slot 108. Lever 40 is
"nested" within the spring, between the coils of spring 90, so that
the assembly of the lever and spring are vertically compact. Pin 49
extends through both slot 46 of the lever and the coil of spring
90.
As handle 30 is forced downward to the position of FIGS. 9 and 10,
slip link 130 presses tab 44, in a sliding relation that
accommodates the arcing motion of the handle about boss 32 and
lever 40 about pin 49. The surface of tab 44 is convex such that
the contact point between curved surface 131 of slip link 130 and
tab 44 includes a radial force component toward pin 49. See tab 44
where slip link 130 is cut away in FIG. 8. A perfectly tangential
contact would not produce any force toward pin 49, only around pin
49. A radial component produces a cam action that exaggerates the
motion of lever 40 with respect to motion of handle 30. The extra
lever motion shows as additional sliding of tab 44 under
curved'surface 131 beyond that which would result just from the
respective arcing of the lever and handle. The cam action functions
as long as there is some inherent sliding at the contact point,
where the sliding is reducing the combined distance from: boss 32
to the contact point at tab 44 to pin 49.
When boss 32, the contact point, and pin 49 are aligned, there is a
neutral condition with no sliding. In FIGS. 9 and 10 the handle and
lever positions are just past this neutral condition. The contact
point has moved forward to a different position of convex tab 44.
The force on tab 44 from curved surface 131 is nearly entirely
tangential about pin 49.
The effect of the above discussion of the contact point is a
varying leverage action of the handle upon the lever. The handle
moves the lever quickly with low leverage at the start of the
stroke, FIGS. 5 to 8. At the end of the stroke, FIGS. 9 and 10, the
leverage of handle 30 is relatively higher upon lever 40. At the
same time the force required to deflect spring 90 increases as
striker 100 is lifted toward the position of FIGS. 9 and 10. Since
the leverage provided by the handle increases through the stroke,
the net force required to operate the handle is relatively
constant, with no hard-to-overcome peak at the end from a highly
deflected spring 90.
FIG. 11 shows a re-set position of the stapler intermediate between
the rest position and the pre-release position. This condition
occurs as handle 30 is lifted after ejection of a staple out of
staple ejection slot 11a. Re-set spring 70 is biased to rotate
lever 40 so that lever front end 48 moves down into alignment with
slot 108 of the striker during a re-set stroke. The lever rear end
including tab 44 moves upward as lever 40 pivots about pin 49. To
provide a smooth re-set action it is necessary that lever end 48
first moves down to top edge 103 of the striker, then secondly
slides down past top edge 103 of striker 100 with little
resistance. Therefore the lever should not be biased forward in
this part of the re-set stroke. To prevent a forward or rearward
bias upon lever 40, re-set spring end 72 is positioned
substantially directly above spring end 74 in body 10 during most
of the re-set stroke. Re-set spring end 72 presses generally upward
at hole 42 of lever 40. However at the end of the re-set stroke a
forward bias is required upon lever 40 to cause lever end 48 to
move into and engage striker slot 108 in a third and final step of
the re-set action. For this purpose body 10 includes a rib 17
extending across a width of the body toward the out-of-plane, or
rear, portion of the lever. In the illustrated embodiment rib 17 is
an element of the right half of housing 10, FIG. 24. However rib 17
could be attached to or part of the left half, FIG. 25, or other
part of the stapler. As lever 40 rises at its rear end the coil of
spring 70 also moves upward. The coil also moves rearward as spring
ends 72 and 74 move apart because of the increasing angle between
the arms of spring 70. At a predetermined position of the re-set
stroke the coil contacts rib 17 and can no longer move up or
rearward. The coil is then presses upward against rib 17, slightly
urged forward by the angle of rib 17, while spring end 72 is biased
to arc up and forward about a center defined approximately by the
axis of the spring coil. The forward element of this bias causes
lever 40 to slide forward upon pin 49 about slot 46. Lever end 48
moves into slot 108 of striker 100.
In the re-set action it is desirable to maintain a downward bias
upon pin 49 by lever 40 so that there is no take-up or "rattle"
within slot 46 as the next power stroke begins. For example if a
re-set spring causes an upward force at pin 49, pin 49 will press
the bottom edge of slot 46. As the power stroke begins slot 46 will
press pin 49 at the opposing upper slot edge. The lever will
unproductively move as slot 46 adjusts about pin 49. To prevent
this wasted motion re-set spring upper end 72 is fitted in lever
hole 42, rearward of tab 44. Hence as slip link 130 presses down on
tab 44, and spring end 72 presses up on the rear end of the lever
at hole 42, all points on the lever forward of tab 44, including
slot 46, are biased downward. A tab notch or other engaging feature
of lever 40 may serve the function of hole 42.
Re-set spring 70 includes features at each end to hold the spring
in place. During assembly lower re-set spring end 74 is normally
installed first into hole 19 of the left half of housing 10, FIG.
25. Hole 19 is larger in diameter than the wire of spring 70.
Spring end 74 includes a short bent segment 74a, FIG. 30 such that
the end 74 including 74a presses the wall of hole 19. This
interference prevents the spring from falling out of hole 19 as the
stapler is assembled. After assembly an opposing rib 174, FIGS. 11
and 24, normally holds spring end 74 in hole 19. Note that spring
end 74 appears uncontained in FIG. 11, since the housing left half
is not shown for clarity. After brief use of the stapler, the
distal end of segment 74a digs a circumferential partial groove in
the wall of hole 19 as end 74 rotates in the axis defined by the
hole. Then end 74 with segment 74a pivots with minimal resistance
in hole 19. Spring upper end 72 includes a simple structure to hole
it in position in hole 42. End 72 extends upward as it passes
through hole 42, as best seen in FIG. 5. As spring 70 presses up
within hole 42, it is drawn toward lever 40 because of the upward
angle of end 72. To further secure the upper spring end from
sliding out of hole 42 a rib of handle 30 extends behind spring end
72 in FIG. 5. This rib does not normally contact the spring except
in the possible case of impact from dropping of the stapler.
During the re-set stroke handle 30 rotates upward as tab 44 presses
handle 30 upward, through slip link 130, from the bias of re-set
spring 70. Handle 30 rotates at recess 12 of body 10 about a boss
32 on each side of the handle. Body 10 preferably includes chamfers
13 aligned with bosses 32, FIGS. 24 and 25. Handle 30 may be
assembled into body 10 by pressing the handle rearward into the
body after all the internal components of the stapler are assembled
but optionally before the two halves comprising body 10 are fully
fastened together. The halves of the upper rear part of body 10
will slightly separate with assistance from chamfers 13 to allow
bosses 32 to pass into recesses 12. A rear edge of bosses 32 may
also be chamfered at chamfers 32a, FIG. 22. By assembling the
handle after both housing halves are fitted together there is no
concern that internal parts can fall out of position as the handle
is moved into place. Optionally handle 30 may include recesses to
fit inward facing bosses in body 10. The assembly function would be
equivalent.
The stapler includes a normal closed position. In the closed
position the body is substantially parallel and spaced from base
20, as shown in most of the Figures of the complete assembly. FIGS.
7, 18 and 19 show spacer spring 52. Tab 54 is an offset feature at
the distal end of the spring. The tab engages opening 84 of track
80. Shoulder 53 is a spring surface adjacent to tab 54. Shoulder 53
presses the bottom of track 80 while adjacent offset tab 54
protrudes into opening 84. Tab 54 will not necessarily contact any
part of opening 84 or track 80 unless there is a lateral force on
the stapler against which the tab is to react. Such force may be
for example from a user pushing sideways as well as down on handle
30, and therefore body 10, where tab 54 presses against edges of
opening 84 with a force directly proportionate to the user's
sideways applied force. See also FIG. 13 where the base and body
have been pivoted slightly apart. The protrusion of tab 54 is
minimal so that tab 54 does not enter the space enclosed by track
80 where tab 54 could interfere with the staple feeding system
within track 80. Spacer spring 52 holds the body of the stapler
above cover plate 50 so that papers can be inserted under the
stapler. Spacer spring 52 may be formed as shown, from a cut out
portion of the material of cover plate 50. In this manner no extra
parts are needed to include the spacer spring. Spring 52 is
preferably tapered from a wide attaching end to a narrower distal
end for efficient energy storage. The tapered design also ensures
that spring 52 is very rigid in the lateral direction, the spring
being fixed laterally, vertically in the page of FIG. 19, in
relation to cover plate 50, while still movable downward,
vertically in FIG. 18. Spring 52 deflects toward cover plate 50 as
body 10 is forced toward base 20 during normal use.
Spring 52 extends upward and forward. The resulting geometry
ensures that spring 52 will not interfere with any papers that are
inserted all the way to sidewalls 23; FIG. 9 shows this subject
well.
Tab 54 aligns in the lateral direction, vertical in FIG. 14, the
stapler front directly over anvil 57 of cover plate 50. Opening 84
is elongated front to back to provide for translation of tab 54
along track 80 as the stapler body pivots toward base 20. Shoulder
53 slides against the bottom of track 80 during the translation.
The distance between tab 54 and hinge connection 22 of base 20,
FIG. 7, defines the moment arm available to align the front of the
body over anvil 57 at the front of cover plate 50. A longer
distance provides more accurate lateral positioning. As discussed
above, spring 52 includes a rigid attachment to cover plate 50 so
that spring 52 can provide secure lateral positioning. In a typical
stapler, sidewalls 23 are bearings that extend forward to form this
moment arm to react against sideways forces. However the closer the
sidewalls are to the anvil, the less cantilever or overreach is
possible to staple toward the center of a paper sheet. In the
present invention paper can extend fully up to small sidewalls 23,
passing under spring 52. A further advantage of the positioning
design of the invention is that base 20 may be plastic resin that
is less stiff than the die cast or steel base typically used. Tab
54 provides a stiff steel element to position a forward portion of
the body. For best effect tab 54 and opening 84 should be similar
in width, into the page of FIG. 7, so that tab 54 will not move
laterally in opening 84. According to the above description, a
single sheet metal element provides four distinct functions: a
cover plate for a base, a spacer spring, a lateral positioner for
the body, and a staple-forming anvil.
Base 20 includes elongated raised under-portion 24 to provide a gap
between a tabletop and the stapler. The gap creates a substantial
area from which to get fingers under and lift the stapler. Front
foot 26 and rear foot 25 are features that serve to hold up raised
portion 24. Raised portion 24 has a convex outer sectional surface
to further facilitate inserting fingers under base 20. To form the
main component of convex base 20 by molding, a reasonably thin wall
must be used according to standard molding practice. The thin wall
creates cavity 27, FIG. 20, enclosed by base cover plate 50. Note
in FIG. 20 the edges of cover plate 50 are enclosed by a thin
tapered wall section of base 20 as cover plate 50 rests on inset
shelf 251. The base of the stapler is thus a smooth solid form on
its exterior. Using a sheet steel cover plate that extends much of
the length of the base creates a laminated structure providing
additional stiffness to the base assembly of FIGS. 18 to 20.
Cover plate 50 is held to base 20 without the use of additional
components or specialized operations. Tab 56 of the cover plate
extends below undercut 256 of base 20, FIG. 18. Ribs 250, or
another part of base 20 near sidewalls 23, create a friction fit to
hold cover plate 50 against shelf 251. Ribs 250 engage
corresponding notches in the cover plate to position cover plate 50
longitudinally, left to right in FIG. 19. To assemble, cover plate
50 is tilted so that tab 56 enters undercut 256. The cover plate is
then lowered at its rear and pressed into place between sidewalls
23. Spacer spring 52 normally provides pressure to hold cover plate
50 down at its rear giving a redundant holding feature. Cavity 27
may include flattened portion 227 to fit a steel bar for additional
weight in the base.
The rear end of the stapler of the invention presents a clean
simple appearance, FIG. 4. Sidewalls 23 are joined by rear wall 29,
FIGS. 14a,b and 17, largely enclosing the lower rear end of body
10. Recess 16 in body 10 fits retractable track pull 60, FIGS. 15
and 16. Sidewalls 23 normally surround these elements so that they
do not show. Body 10 rotates about post 15 at hinge connection
recess 22 on sidewalls 23. Post 15 is seen best in FIGS. 12 and
14c. Hinge connection 22 is seen best in FIGS. 14c and 17. These
features are shown as hidden lines in FIGS. 15 and 16 for
reference. Alternately the post may extend from sidewalls 23, while
the recessed hinge connection may be in body 10. In the illustrated
embodiment track pull 60 includes extension 67. As the stapler body
is forced to pivot about hinge connection 22, extension 67 passes
against an upper edge of wall 29, FIG. 14b. Wall 29 forms a detent
to control the motion of the body pivoting from the base. In a
normal rest position, where body 10 is upright above base 20,
spring 52 holds the body up in a body rest position to provide
clearance for papers, with spring 52 being held slightly deflected
down by the detent formed by extension 67 against wall 29 below
hinge of pivotal attachments 15 and 22. Further upward force
overcomes the resistance of the detent to unload the spring and
allow the body to be fully pivoted behind the base, to an upside
down and rearward extending position, FIG. 15. With the
above-described structure, the mechanism used for loading staples
is not visible until it is needed.
Using extension 67 to hold the body with a slight preload on spring
52 provides a stiff structure. If for example, the body were held
down at tab 54 of spring 52 by a frictional engagement between tab
54 and opening 84, the body would bounce over the base since an
unloaded spring is doing all of the holding. This would suggest low
quality design.
Squeezing track pull arms 65 releases track locks 62 from catches
262, FIGS. 16 and 24, of the body. The track can now be pulled
rearward by retracting track pull 60, FIG. 16, to expose staple
loading chamber 144. In the open position the body is upside down
and rearward of the base, FIG. 15. Track pull 60 is now above hinge
connection 22, facing forward or oppositely from its normal
rearward orientation under the hinge, FIG. 14a. Using extension 67
of track pull 60 adds resiliency to the detent system that engages
rib 29 since the track pull is slightly movable within recess 16 in
the normal engaged position of track pull 60, FIGS. 14a,b.
Resiliency within a detent action enhances the feel and reliability
of the detent action since some give is needed for the detent to
release. Alternately extension 67 could be a direct element of body
10 or further component of the stapler. If extension 67 were rigid
it could be desired that rib 29 be a resilient cantilevered tab of
base 20 created by, for example, two parallel vertical slots in rib
29 near sidewalls 23 with respect to the view of FIG. 20.
Staple pusher 180 fits over track 80 to urge staples, not shown,
that are guided by track 80 toward striker 100, FIGS. 31 and 32.
Extension spring 300 is secured at a spring front end under loop 81
of the track. A rear end of the spring attaches to pusher 180 to
urge the pusher forward. Spring 300 is represented schematically by
a single typical coil of spring 300. Spring 300 in fact extends
axially within the space enclosed by track 80 and pusher 180.
Although spring 300 is a low force spring, it must store energy
over a long distance to urge every staple in a long rack of staples
forward. For example a typical rack of standard staples is about 4"
long. So spring 300 must extend 4", from its rest position, while
maintaining a preloaded bias force in the rest position. The spring
rest position corresponds to the last single staple of the rack of
staples when pusher 180 is fully forward. In the Figures, the
pusher is shown near to the spring rest position.
To store the most energy spring 300 needs a maximum number of coils
and maximum coil diameter, to effectively pack the longest possible
wire in the available space. This possible wire length is a
function of the overall length of track 80 and an internal area
enclosed by both the track and the pusher that can fit the coil
diameter. The internal transverse sectional area of the track with
pusher is determined by the size of the staples that the track is
designed to carry. A wider track will not fit within a specified
staple leg dimension, and a taller track will require striker 100
to rise higher than necessary to clear the top of the staples,
requiring a taller overall stapler device since striker channel
upper end 11b would need to be higher. Standard desktop staples are
relatively wide and short compared to tacker staples.
According to the present invention, a larger interior space
enclosed by the track for the coil of spring 300 is provided by
creating an effectively taller space, while still fitting wide
short staples. In FIGS. 31 and 32 the bottom of track 80 is not
flat, having an elongated crease 85. In the prior designs, the
level of the bottom of the track has been the same as tabs 87,
which fit into channels 287FIGS. 24 and 25. There is a rib 287a
under channel 287 defining a gap between tab 87 and the underside
of housing 10. See also FIG. 13. It is important that the track
does not protrude below the underside of the housing since the
track would hold the housing away from papers to be stapled.
However the thickness of rib 287a is an available space into which
the track may protrude without interfering with the function. In
FIGS. 31 and 32 the center of track 80 is lowered at crease 85, by
part of the thickness of rib 287a. This lowered portion allows
increased diameter for the coil of spring 300, where spring 300 is
centered across the width of track 80.
To further increase the available spring area, pusher 180 includes
centrally aligned arcuate hump 185 co-axial with the coils of
spring 300. Arcuate channel 145, FIGS. 24, 25 and 33, extends into
ceiling 142 of loading chamber 144. In FIG. 33 staples 400 are
shown in front of pusher 180. Ceiling 142 provides an upper
vertical confinement for holding staples 400 on track 80. However
such confinement need only be at each side of the staple, so hump
185 may protrude up, with lower shoulders to each side at the
conventional height, providing extra space for the coil of spring
300. Hump 185 need not be precisely arcuate or precisely co-axial
with spring 300.
Tabs 87 are formed from cutouts 82 of the bottom of track 80. Rib
89 forms a divider between cutouts 82. This design contrasts with
that of U.S. Pat. No. 5,699,949 where the tabs are formed from
cutouts of the track sides. Using cutouts from the bottom is
desirable in the present invention light duty stapler where the
staples and thus the track sides are short compared to staple gun
tackers. Forming the tabs from the sides would leave little
material on the side. Rib 89 provides stiffness to the bottom of
the track.
Bumper 146 provides a stop for power spring 90, FIGS. 6 and 25. The
impact force from spring 90 is directed toward the outer portions
of housing 10 since the power spring is in two separate spaced arms
at striker 100. The outer portion is the thicker areas of ceiling
142, away from channel 145, FIG. 33. So ceiling 142 provides good
support for bumper 146. The left and right halves of housing 10 may
be fastened with screws, welds, glue, or other well-known means. In
the illustrated embodiment, serrated posts or holes are used. The
left half of housing 10, FIG. 25, includes three serrated posts
18a, and one serrated hole 18d. The right half, FIG. 24, includes
three smooth holes 18b and one smooth post 18c. With one element of
each pair serrated, a reliable interference fit is possible to
press the housing together, as the sharp edges of the serrations
are gently crushed. The interference fit holds the assembly
together as ultrasonic welding or glue are used to securely bond
the housing halves. Such bonding may be on the posts directly or
other areas of housing 10.
Hinge connection 22 with post 15 is shown in section in FIG. 14c,
with the individual elements in FIGS. 12 and 17. Post 15 includes a
main diameter and extends from both left and right housings 10.
Posts 15 include a tapered end with small diameter end 15a. Small
end 15a engages small end 22a of hinge connections 22. The
respective small end diameters are preferably the same. Optionally
the taper leading to small end 15a is steeper than that of 22a.
Further the spacing of sidewalls 23 with hinge connections 22 may
be slightly smaller than the distance between left- and right-side
posts 15. Then small ends 15a will be pressed by small ends 22a.
The effect is then similar to a needle bearing, where small ends
15a are precisely located by wedging within the recesses of hinge
connections 22, at 22a. Since the diameters of the small ends are
much reduced from the main diameters of the associated features,
there is minimal friction against rotation even as there is some
wedging. This precise locating works with the moment arm discussed
above with respect to tab 54 and opening 84 to position the front
end of the stapler over anvil 57.
For assembly, housing 10 is forced in-between sidewalls 23. The
tapered ends of posts 15 form ramps to spread apart sidewalls 23 as
posts 15 begin to press edges of sidewalls 23 during assembly.
Hinge connections 22 are at movable portions of sidewalls 23, FIG.
17, since there is no cross member adjacent to connections 22 to
rigidly bind them in relative position. The closest such member is
rib 29. Therefore no separate fasteners are required to connect
housing 10 to base 20.
* * * * *